Electrochemical cells, such as fuel cells, generate electrical power through the electrochemical reaction of a fuel and an oxidant. An exemplary fuel cell has a membrane electrode assembly (MEA) with catalytic electrodes and a proton exchange membrane (PEM) sandwiched between the electrodes. In preferred PEM type fuel cells, hydrogen is supplied as a reductant to an anode and oxygen is supplied as an oxidant to a cathode. PEM fuel cells reduce oxygen at the cathodes and generate an energy supply for various applications, including vehicles.
It is well established that channel water accumulation, in both the anode and cathode flow field plates, significantly influences fuel cell performance at low loads. When the gas velocities are relatively low (i.e., less than about 5 meters per second), the water transported through channels of diffusion media favors the formation of liquid droplets that occupy a significant portion of the channel cross-section. These droplets increase the gas flow resistance in particular channels, thereby diverting flow to neighboring channels and essentially starving the local active area of necessary reactants. Various means of circumventing this potential problem have been explored and have included altering the physical characteristics of the channels, including the channel geometry, specifically the size and shape. There remains a need for improved water management to improve fuel cell performance, efficiency, and lifespan.